Safe operation of a vehicle requires constant attention to the road and the environment surrounding the vehicle. A driver may encounter many obstacles while driving, not only at busy urban intersections, but virtually anywhere. Even the most attentive driver may not see someone coming at the last moment. Some driver assistance systems help drivers by detecting pedestrians in proximity to a vehicle and alerting drivers of the pedestrians' presence. However, such systems typically alert drivers of all pedestrians within the field of view of the system. The feedback provided is rarely more useful, or less overwhelming, than the actual situation as the driver sees it through the windshield.